docstr: For SavedModel support: returns the default serving signature.
docstr_tok: ["For","SavedModel","support",":","returns","the","default","serving","signature","."]
code: def _default_save_signature(self):
      """For SavedModel support: returns the default serving signature."""
  
      from keras.models.functional import Functional
      from keras.models.model import Model
      from keras.models.sequential import Sequential
  
      if not isinstance(self, Model):
          return None
  
      inputs = None
      if (
          isinstance(self, Sequential)
          and getattr(self, "_functional", None) is not None
      ):
          inputs = self._functional.input
      elif isinstance(self, Functional):
          inputs = self.input
  
      if inputs is not None:
          input_signature = [
              tf.nest.map_structure(
                  lambda x: tf.TensorSpec(x.shape, self.compute_dtype),
                  inputs,
              )
          ]
      else:
          shapes_dict = self._build_shapes_dict
          if len(shapes_dict) == 1:
              input_shape = tuple(shapes_dict.values())[0]
              input_signature = [
                  tf.TensorSpec(input_shape, self.compute_dtype)
              ]
          else:
              input_signature = [
                  tf.nest.map_structure(
                      lambda x: tf.TensorSpec(
                          x.shape, self.compute_dtype
                      ),
                      shapes_dict,
                  )
              ]
  
      @tf.function(input_signature=input_signature)
      def serving_default(inputs):
          return self(inputs)
  
      return serving_default
  
file_path: keras/keras/backend/tensorflow/layer.py
imports: import tensorflow
  from keras.backend.tensorflow.trackable import KerasAutoTrackable
  from keras.utils import tf_utils
  from keras.utils import tracking
label_desc: Use image node_id 4 for calling the TFLayer obj's underlying member method code with example usage: obj._default_save_signature() and returns: serving_default, None, self